Study on the Behavior of Concrete with waste Tire Wire as Fibers

Abstract

Steel fiber reinforced concrete (SFRC) is cement based composite material. Basically, the concrete has low tensile strength, low strain capacity, and it fails in brittle manner. Different types of steel fiber (industrially manufactured and recovered from different used materials) are used in concrete to modify the tensile strength of concrete. The addition of the fiber improves the mechanical properties of concrete, especially the post-cracking properties. It is known that fibers bridge the cracks and transfer the tensile stress across the cracked sections. Therefore, the concrete becomes more ductile and durable material in resisting tension. In this research work, the effect of addition of recovered steel fiber (the Bead wire) from waste tire on the mechanical behavior of concrete was investigated to quantify the advantages obtained by the concept of SFRC with concrete. Experimental (compression, workability and split) and finite element analysis method (post cracking response in terms of load-displacement) was used for the investigation. The effect on flexure (on post cracking response in terms of Load-displacement) was analyzed by finite element method, using ABAQUS Software. For Modeling, the SFRC constitutive model proposed by Lok and Xiao (1999) was adopted. The stress and strain values for compressive and tensile behavior were calculated using the formula proposed by aforementioned model’s formula. The values of ft for calculation, in formula were obtained from laboratory test result. The reliability of the FE numerical model predictions was ensured by calibrating it against existing experimental data. A total of twelve beams of 1.70 m length and 180mm x 100mm in cross-section were modeled and analyzed in ABAQUS for this study. For each grade of concrete one beam served as control beam (without fiber) and other three beams were modeled with different fiber volume fraction (1.0% 1.5%, & 2%). Also compressive and tensile strength test were performed experimentally. Different grade of concrete (C20, C25 and C30) and different steel fiber (bead wire having a diameter of 0.89 mm extracted from used tires with aspect ratio of 67) volume fractions (1.0% 1.5%, & 2%) were the principal parameters considered in this study. All the beams were analyzed under four-point bending in a loading. The results showed that addition of RSF to concrete greatly reduces the workability of concrete, increased the compression in fewer amounts, maximum increment was observed in C-30-2.0 mix on third specimen (37.76%) and minimum increment was observed in C-30 -1.0 mix on third specimen (35.16%). The tensile strength of RSFC also highly increased as the ratio of RSF increased. Maximum increment of tensile strength was seeing on C-25- 2.0 mix in the third specimen which is 140.49% and the minimum increase was observed in C-30-1.0 mix on the third specimen which is 60.07%. The post-crack were greatly increased with fold due to the presence of steel fibers.